Update main Python version to 3.13

[greschd]

Currently blocked by sphinx-doc/sphinx#13178.

We could presumably fix that by upgrading to Sphinx 8.2.0, but that would require dropping Python 3.10 support on the doc build.
Alternatively, we could ignore the resulting warning.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.96%. Comparing base (1d62321) to head (1995d1a).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #841   +/-   ##
=======================================
  Coverage   93.96%   93.96%           
=======================================
  Files         110      110           
  Lines        5915     5915           
  Branches      329      329           
=======================================
  Hits         5558     5558           
  Misses        351      351           
  Partials        6        6           

Flag	Coverage Δ
direct-launch	91.10% <ø> (ø)
minimum-deps	92.06% <ø> (ø)
python-3.10	93.13% <ø> (ø)
python-3.11	93.06% <ø> (ø)
python-3.12	93.06% <ø> (ø)
python-3.13	93.30% <ø> (ø)
server-2024R2SP5	89.55% <ø> (ø)
server-2025R1SP4	93.10% <ø> (ø)
server-2025R2SP3	93.06% <ø> (ø)
server-2026R1	93.06% <ø> (ø)
server-latest	93.72% <ø> (ø)

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